Performance of a solar thermal power plant with direct air-cooled supercritical carbon dioxide Brayton cycle under off-design conditions

•A method of design and rating of the sCO2 dry-cooling system is presented.•The dry cooling system well predicts performance of an existing cooling tower.•A solar driven direct air-cooled sCO2 cycle power plant is studied.•The performance of operating and boundary conditions, and part load is analyzed.•The effect of solar irradiation drop is eliminated when above a critical DNI.